Rotating filter for a dishwashing machine

Abstract

A dishwasher with a tub at least partially defining a washing chamber, a liquid spraying system for spraying liquid within the washing chamber, a liquid recirculation system defining a recirculation flow path, and a liquid filtering system. The liquid filtering system includes a rotating filter disposed in the recirculation flow path to filter the liquid.

What is claimed is: 
     
       1. A method of operating a dishwasher comprising a washing chamber holding utensils for washing, sprayers for spraying liquid on the utensils, and a liquid recirculation system, for recirculating sprayed liquid back to the sprayers, and including a filter for filtering the liquid, the method comprising:
 spraying liquid within the washing chamber; 
 recirculating the sprayed liquid for subsequent spraying; 
 providing a filter within the recirculating liquid where the filter completely fluidly divides the recirculating liquid such that the filter has an upstream surface confronting unfiltered liquid and a downstream surface confronting filtered liquid; 
 providing an artificial boundary spaced apart from at least a portion of the upstream surface to form a gap between the artificial boundary and the upstream surface; and 
 rotating the filter within the liquid during the recirculating of the liquid; 
 wherein the liquid passing between the artificial boundary and the rotating filter caused by rotation of the filter applies a shear force on the upstream surface that is greater than the liquid in an absence of the artificial boundary 
 and aids in a removal of soils on the upstream surface. 
 
     
     
       2. The method of  claim 1  wherein the applying the shear force comprises locally increasing the shear force attributable to an interaction of the liquid, the artificial boundary and the rotating filter. 
     
     
       3. The method of  claim 1  wherein providing the artificial boundary comprises providing an artificial boundary that forms a high pressure area between the artificial boundary and the upstream surface. 
     
     
       4. The method of  claim 1  wherein the liquid passing between the artificial boundary and the rotating filter caused by rotation of the filter also generates a backwash through the filter from the downstream surface to the upstream surface along at least a portion of the filter. 
     
     
       5. The method of  claim 4  wherein the liquid passing between the artificial boundary and the rotating filter caused by rotation of the filter generates a lower pressure on the upstream surface than on the opposing portion of the downstream surface. 
     
     
       6. The method of  claim 5  wherein recirculating the sprayed liquid forms a stream of liquid passing through the filter, from an upstream side to a downstream side, at a location rotationally in front of the backwash liquid flow, generated by the rotation of the filter, such that at least a portion of the stream of liquid becomes part of the backwash liquid flow and is returned to the upstream side of the rotating filter. 
     
     
       7. The method of  claim 1 , further comprising providing another artificial boundary on a downstream side of the filter such that the proximity of the another artificial boundary and the downstream surface applies a shear force on the downstream surface to aid in the removal of soil on the downstream surface, with a magnitude of the shear force being greater than the shear force attributable to the filter rotating in liquid in an absence of the another artificial boundary. 
     
     
       8. A method of operating a dishwasher comprising a washing chamber holding utensils for washing, sprayers for spraying liquid on the utensils, and a liquid recirculation system, for recirculating sprayed liquid back to the sprayers, and including a filter for filtering the liquid, the method comprising:
 spraying liquid within the washing chamber; 
 recirculating the sprayed liquid for subsequent spraying; 
 providing a filter within the recirculating liquid where the filter completely fluidly divides the recirculating liquid such that the filter has an upstream surface confronting unfiltered liquid and a downstream surface confronting filtered liquid; 
 providing an artificial boundary spaced apart from at least a portion of the upstream surface or the downstream surface to form a gap between the artificial boundary and the upstream surface or the downstream surface; and 
 rotating the filter within the liquid during the recirculating of the liquid; 
 wherein the liquid passing between the artificial boundary and the rotating filter caused by rotation of the filter generates a backwash through the rotating filter from the downstream surface to the upstream surface along at least a portion of the filter 
 and aids in a removal of soils on the upstream surface. 
 
     
     
       9. The method of  claim 8  wherein the liquid passing between the artificial boundary and the rotating filter caused by rotation of the filter generates a lower pressure on the upstream surface than on an opposing portion of the downstream surface. 
     
     
       10. The method of  claim 9  wherein the liquid passing between the artificial boundary and the rotating filter generates a high pressure area on the downstream surface or generates a low pressure area on the upstream surface. 
     
     
       11. The method of  claim 10  wherein the providing the artificial boundary comprises locating the artificial boundary on a downstream side of the rotating filter and the liquid passing between the artificial boundary and the downstream side of the rotating filter caused by rotation of the filter generates a high pressure area. 
     
     
       12. The method of  claim 11 , further comprising providing another artificial boundary on an upstream side of the rotating filter and the liquid passing between the another artificial boundary and the upstream side of the rotating filter cause by rotation of the filter generates a low pressure area opposite the high pressure area. 
     
     
       13. The method of  claim 8  wherein recirculating the sprayed liquid forms a stream of liquid passing through the filter, from an upstream side to a downstream side, at a location rotationally in front of the backwash liquid flow generated by the rotation of the filter such that at least a portion of the stream of liquid becomes part of the backwash liquid flow and is returned to the upstream side of the rotating filter.